Munira Khan ; Florian Bernlochner ; Jochen Dingfelder ; Markus Prim

28 February 2024
DPG-Frühjahrstagung 2024

Abstract: The determination of the Cabibbo-Kobayashi-Maskawa matrix element |𝑉𝑐𝑏| relies on 𝑏 → 𝑐ℓ𝜈ℓ transitions. The inclusive semileptonic process can be described with the Heavy Quark Expansion (HQE) and using the operator product expansion the total decay rate can be parameterized with a small number of non-perturbative parameters. These parameters cannot be determined from first principles, but their values are encoded into kinematic moments of the decay rate. In this talk we present the current status of measuring the full set of kinematic moments (𝑞2, 𝑀𝑋 , 𝐸ℓ, 𝑛𝑋 ) within a single analysis, which characterize the semileptonic 𝑏 → 𝑐ℓ𝜈ℓ and 𝑏 → 𝑞ℓ𝜈ℓ transitions using the Run 1 data of the Belle II experiment. This allows for the first time to properly correlate experimental uncertainties. In addition, we present preliminary fits for |𝑉𝑐𝑏| to simulated samples to illustrate the increase in sensitivity of this approach.